116 Keysight InfiniiVision 1200 X-Series and EDUX1052A/G Oscilloscopes User's Guide
11 Triggers
 
To trigger on odd or even fields
To check the envelope of your video signals, or to measure worst case distortion, 
trigger on the odd or even fields. When Field 1 is selected, the oscilloscope 
triggers on color fields 1 or 3. When Field 2 is selected, the oscilloscope triggers 
on color fields 2 or 4.
1 Press the [Trigger] key.
2 In the Trigger menu, press the Trigger Type softkey.
3 Press the Trigger Type softkey; then, turn the Entry knob to select Video.
4 Press the Settings softkey, then press the Standard softkey to select the 
appropriate TV standard.
5 Press the Mode softkey and select Field1 or Field2.
The trigger circuits look for the position of the start of Vertical Sync to determine 
the field. But this definition of field does not take into consideration the phase of 
the reference subcarrier. When Field 1 is selected, the trigger system will find any 
field where the vertical sync starts on Line 4. In the case of NTSC video, the 
Figure 18 Triggering on All Fields